Many portable products, such as cell phones, laptop computers, personal digital assistants (PDAs) or the like, incorporate a processor executing a program supporting communication and multimedia applications. The processing system for such products conventionally includes a number of components that communicate using a bus.
A conventional processing system includes one or more processors, associated memory, and a number of peripheral devices determined by product requirements. Such a processing system may use multiple buses with an individual bus utilized between components according to the data transfer rates expected between the components. For example, one of the individual buses may be a shared bus or a point-to-point bus. A shared bus is connected to multiple components and provides a means for the multiple components to communicate over a common shared channel. A point-to-point bus-uses a switching connection between multiple components and provides a switched direct connection path between any two selected components. Multiple direct connection paths may be selected to allow several components to communicate in parallel.
The conventional shared bus and point-to-point bus include separate read data, read address, read control, write data, write address, and write control channels. For example, a processor may write data to a memory or a peripheral by placing a write address value on the write address channel, write data on the write data channel, and controlling write qualifier signaling on the write control channel. The processor may also read data from a memory or peripheral device by placing a read address value on the read address channel, receiving read data on the read data channel, and controlling read qualifier signaling on the read control channel.
Although such bus structures provide a standardized way to communicate between components of the processing system, such bus structures require a large number of interface signals. These interface signals require support circuits, such as drivers, receivers, buffers, and control circuits, all of which consume power. In integrated circuit applications, the wiring and support circuits for these interface signals occupy valuable chip area.